Put transform tree building in DisplayItemPropertyTreeBuilder.

public/platform/WebDisplayItemTransformTree.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WebDisplayItemTransformTree_h
 #define WebDisplayItemTransformTree_h
 
 #include "public/platform/WebCommon.h"
 #include "public/platform/WebFloatSize.h"
 #include "public/platform/WebPrivateOwnPtr.h"
 #include "third_party/skia/include/utils/SkMatrix44.h"
 
 namespace blink {
 
 class DisplayItemTransformTree;
 
 // Represents the hierarchy of transforms which apply to ranges of a display
 // item list and may be of interest to the compositor.
 //
 // It consists of a tree of "transform nodes", stored in a flattened
 // representation in which their order is not guaranteed. Each node has a
 // parent, relative to whom its transform should be interpreted (i.e. the
 // total transform at a node is the product of its transform and its parent's
 // total transform).
-//
-// These nodes are associated with a display item list through the associated
-// "range records", which correspond to non-overlapping ranges of display items
-// in the list, in sorted order. Since the begin/end display items that create
-// transform nodes are not included in these ranges, and empty ranges are
-// omitted, these ranges are not a partition. Rather, they constitute a partial
-// map from display item indices to transform node indices.
-//
-// Similarly, there may be transform nodes with no associated range records.
-// This doesn't necessarily mean that it can be ignored -- it may be the parent
-// of one or more other transform nodes.
-class WebDisplayItemTransformTree {
+class BLINK_PLATFORM_EXPORT WebDisplayItemTransformTree {
 public:
     enum : size_t { kInvalidIndex = static_cast<size_t>(-1) };
 
     struct TransformNode {
         TransformNode(size_t parent, const SkMatrix44& matrix44)
             : parentNodeIndex(parent)
             , matrix(matrix44)
         {
         }
 
         bool isRoot() const { return parentNodeIndex == kInvalidIndex; }
 
         // Index of parent in m_nodes (kInvalidIndex for root).
         size_t parentNodeIndex;
 
         // Transformation matrix of this node, relative to its parent.
         SkMatrix44 matrix;
     };
 
-    struct RangeRecord {
-        RangeRecord(size_t beginIndex, size_t endIndex, size_t nodeIndex, const WebFloatSize& drawingOffset = WebFloatSize())
-            : displayListBeginIndex(beginIndex)
-            , displayListEndIndex(endIndex)
-            , transformNodeIndex(nodeIndex)
-            , offset(drawingOffset)
-        {
-        }
-
-        bool operator==(const RangeRecord& other) const
-        {
-            return displayListBeginIndex == other.displayListBeginIndex
-                && displayListEndIndex == other.displayListEndIndex
-                && transformNodeIndex == other.transformNodeIndex
-                && offset == other.offset;
-        }
-        bool operator!=(const RangeRecord& other) const { return !(*this == other); }
-
-        // Index of first affected display item.
-        size_t displayListBeginIndex;
-
-        // Index of first unaffected display item after |displayListBeginIndex|.
-        size_t displayListEndIndex;
-
-        // Index of a the applicable transform node (in |m_nodes|).
-        size_t transformNodeIndex;
-
-        // The offset of this range's drawing in the coordinate space of the
-        // transform node.
-        WebFloatSize offset;
-    };
-
-    BLINK_PLATFORM_EXPORT WebDisplayItemTransformTree();
+    WebDisplayItemTransformTree();
 #if INSIDE_BLINK
-    BLINK_PLATFORM_EXPORT WebDisplayItemTransformTree(
-        const WTF::PassOwnPtr<DisplayItemTransformTree>&);
+    WebDisplayItemTransformTree(const WTF::PassOwnPtr<DisplayItemTransformTree>&);
 #endif
 
-    BLINK_PLATFORM_EXPORT ~WebDisplayItemTransformTree();
+    ~WebDisplayItemTransformTree();
 
     // Returns the number of nodes in the transform tree.
-    BLINK_PLATFORM_EXPORT size_t nodeCount() const;
+    size_t nodeCount() const;
 
     // Returns a node in the transform tree by its index (from 0 to nodeCount() - 1).
-    BLINK_PLATFORM_EXPORT const TransformNode& nodeAt(size_t index) const;
-
-    // Returns the parent of the given node.
-    // Do not call this with the root node.
-    BLINK_PLATFORM_EXPORT const TransformNode& parentNode(const TransformNode&) const;
-
-    // Returns the number of display item ranges.
-    BLINK_PLATFORM_EXPORT size_t rangeRecordCount() const;
-
-    // Returns the requested display item range, sorted by position in the
-    // display item list.
-    BLINK_PLATFORM_EXPORT const RangeRecord& rangeRecordAt(size_t index) const;
+    const TransformNode& nodeAt(size_t index) const;
 
 private:
     WebPrivateOwnPtr<const DisplayItemTransformTree> m_private;

[pdr., 2015/08/17 22:25:08]

Why "m_private" instead of "m_transformTree"?

[jbroman, 2015/08/17 23:57:19]

The majority of cases of this pattern use that name:
https://code.google.com/p/chromium/codesearch#search/&q=file:%5Esrc/third_par...

[pdr., 2015/08/18 04:31:42]

Sadness. But, when in Rome..

 };
 
 } // namespace blink
 
 #endif // WebDisplayItemTransformTree_h